Tom McGean walks his dog, Ghost, near 16th and Wewatta streets on May 17, 2018. An estimated 1,700 dogs will soon live in the Union Station and Riverfront Park areas, between Union Station and Commons Park. This has caused some problems, including dead plants and trees as dogs with nowhere else to go relieve themselves in the few green spaces that exist.

When a city has, in the literal sense, long past gone to the dogs, it gets harder for some of those pups to find places when they really, well, have to go.

As new high-rises in mutt-loving Denver’s urban neighborhoods draw thousands of human residents, local leaders fear that the pooches coming with them — combined with too few places to do their business — could spell death for prized trees and other urban greenery.

“Our dogs and owners don’t quite get to the dog park or to the park in time, and boy, I’ll tell you — that patch of grass on the corner is under siege,” said Don Cohen, a longtime Riverfront Park neighborhood advocate.

In that area and in the blocks closer to Union Station, across the freight-rail tracks, neighborhood leaders are responding to the canine influx with new strategies. This summer, separate pilot projects will aim to gently guide dogs away from trees and other landscaping planted along the streets before they raise a leg or take a squat.

Here’s a rough estimate: 1,200 dogs soon will be among the occupants of the roughly 3,000 apartments and other residences that have been built or are under construction behind Union Station, according to research cited by Amy Cara, a developer. She’s also president of the Central Platte Valley Metropolitan District, which oversees most public spaces in that area.

Add in the riverfront area, and the dog-census estimate soars well past 2,000 — all packed into fewer than 20 blocks.

Cohen, the president of the Riverfront Park Association, says it spends about $30,000 a year to replace urine-ravaged grass with fresh sod. The worry is that trees could begin dying after prolonged assaults.

As dogs hunt for inviting spots, they soon will find short fencing surrounding some green spaces, and possibly raised planter boxes built atop others. Their owners will begin hearing more from neighborhood leaders about pet-relief restrictions as part of outreach campaigns.

And, because it’s an unavoidable need that Cara and Cohen said they’re working on longer-term, residents could start to notice more official and unofficial spots where it’s OK for pets to piddle.

One idea that has been raised for the Union Station area, but not yet embraced, is converting single street-parking spaces to dog areas.

“The idea is that you can’t just say ‘no’ to dogs and be like, ‘OK, there’s no place for you,’ ” said Cara, a managing partner of the Denver office of East West Partners, a major developer in the area. “But we do need to protect the trees, or we won’t have trees. We need to make sure there is an alternate place to go, because most dogs will not go on the sidewalk.”

AAron Ontiveroz, The Denver Post

A man walks a dog on Chestnut Place downtown on May 17, 2018.

Oliver, a 4-year-old golden retriever, is a pro at holding it until he reaches Commons Park, said his owner, Jessica Forrest.

“He’s lived in apartments his whole life, so he knows where’s OK to go and where is not,” said Forrest, 26, who moved to the Union Station neighborhood last year from another part of Denver. She and Oliver were returning to her Chestnut Place apartment on a walk Wednesday night.

It took awhile for Forrest to make the park a part of Oliver’s routine. “Actually, when I first moved here,” Forrest said, “I did find it a bit challenging because really the only green space (on this side of the tracks) was right over here by the Whole Foods (on 17th Street). And they put up all the signs saying they didn’t want us actually using it.”

Plenty have ignored those signs. The toxicity of urine is the main concern, since the owners generally bag up the solid waste deposited by their pets.

Even in the Riverfront Park area, where every building is a short walk from the 30-acre Commons Park and the dirt-patch Railyard Dog Park, wayward dog urination is a challenge.

There are even fewer options amid all the concrete near Union Station, although some buildings provide small dog runs. Taking the brunt — despite posted signs marking all the vegetated space as off-limits — are small landscaped areas along the street and in the 17th Street Gardens, built atop the Regional Transportation District’s underground bus terminal.

Provided by Livable Cities Studio

A concept design under consideration in the Union Station neighborhood would protect street trees by surrounding them with shrubs and fencing. A crushed-stone surface on the perimeter would be available for dogs to urinate.

Both the Riverfront Park group and the Central Platte Valley district have hired contractors to research options tried out in urban neighborhoods in Chicago, New York City and elsewhere.

“We know that this answer is probably going be in the hundreds of thousands of dollars over time to come up with a solution,” Cohen said.

Both neighborhoods have sprouted high-rises where a jumble of rail yards and viaducts once stood between Union Station and the South Platte River.

Cara referred to the dog challenge as an unforeseen consequence of new development, in part because original plans anticipated mostly office buildings.

The city’s Department of Public Health and Environment counts just 28,337 active dog licenses citywide, but a spokeswoman said a small fraction of owners actually register their dogs. Based on a commonly used pet-ownership formula, the department estimates that Denver has 89,144 dog-owning households, with an estimated dog population of nearly 143,000.

Across the river in Highland, managers of newer midrise apartment buildings have dealt with a similar pooch-pee challenge. Their favored solution has been replacing brown-spotted grass with AstroTurf, although that can result in strong stenches on hot days unless the turf is hosed down frequently.

That option, for now, has gained little appeal in Riverfront Park and Union Station, with the neighborhood groups favoring measures that preserve real vegetation.

In the blocks near Union Station, the pilot project probably will include modifying up to a dozen landscaped sidewalk areas near apartment buildings by taking a hybrid approach, said Todd Wenskoski of Livable Cities Studio, which is advising Cara’s group.

Plans call for planting shrubs around the trees, then surrounding those with low fences similar to what the New York City parks department uses. Wenskoski says a crushed-stone surface will surround the fencing — a plan intended to provide a hospitable space for dogs in need of relief, just far enough from the trees to protect them.

Jon Murray is an enterprise reporter on The Denver Post's government and politics team, with a focus on transportation. He previously covered Denver Mayor Michael Hancock and city government. A Colorado native, he joined The Denver Post in 2014 after reporting on city government and the legal system for The Indianapolis Star.